1. Field of the Invention
The invention relates to adapters for power line communication systems, in particular, the invention relates to adapters that connect a power line network modem to an electrical outlet or electrical power cord.
2. Description of the Related Art
The widespread availability of computers, especially personal computers, has led to a rapid increase in the number of computer networks. Networking two or more computers together allows the computers to share information, file resources, printers, etc. Connecting two or more personal computers and printers together to form a network is, in principle, a simple task. The computers and printers are simply connected together using a cable, and the necessary software is installed onto the computers. In network terminology, the cable is the network medium and the computers and printers are the network nodes. Unfortunately, in practice, creating a computer network is often not quite as simple as it sounds. Typically, a user will encounter both software and hardware problems in attempting to configure a computer network.
When configuring a network in a home or small office, users often encounter hardware difficulties insomuch as it is usually necessary to install a network cable to connect the various network nodes. In a home or office environment, it can be very difficult to install the necessary cabling when the computers are located in different rooms or on different floors. Network systems that use radio or infrared radiation are known, but such systems are subject to interference and government regulation, and thus are far less common than systems that rely on a physical connection such as a wire or cable.
Virtually all residential and commercial buildings in the U.S. Are wired with electrical power lines, and using the existing power lines as a network medium to carry data is both convenient and efficient. Access to the power lines, for both power and data, is typically provided by conventional two-pronged or three-pronged electrical outlets. In most homes and office buildings, several electrical outlets are provided in each room. Nevertheless, many people find that there are never enough available outlets. To combat this problem, a wide variety of multi-outlet adapters have been marketed.
The multi-outlets adapters come in many forms, but they all have the common goal of expanding the number of devices that can be plugged into a wall outlet. One common type of multi-outlet adapter used with computer equipment is the surge-suppressor strip. The surge-suppressor strips usually include a power cord that plugs into an existing wall outlet, a switch, a circuit breaker, and several outlets. The surge-protector strips include surge suppressors and noise filters to protect the computer equipment from voltage spikes and noise often present on the power line.
Unfortunately, the surge suppressors and noise filters in the surge-suppressor strips often cause problems with power line networking systems because the noise filter treats the network data signals as noise that must be removed. Therefore, it is often desirable for the power line networking system to have direct access to the electrical power outlets, rather than the outlets provided by the surge-suppressor strip.
Power line network systems are often installed by homeowners and small business owners who have little, if any, technical training. Some users have encountered difficulty, and dissatisfaction, with prior power line network systems because the user, unwilling to give up an electrical outlet, plugged the power line equipment into a surge-suppressor strip (sometimes rendering the power line network equipment partially inoperative due to the noise filters in the strip). Moreover, previous embodiments of power line adapters have met with some consumer resistance because the need for direct access to the power outlet “used up” an outlet that the consumer wanted to use for other purposes. In some cases, the size existing power line equipment that plugged into an electrical outlet forced the user to move furniture away from the outlet (such situations can occur, for example, when the outlet being used for a computer or printer lies behind a desk or bookcase).